Assets (such as money, products, or information) which are accessible via a network are vulnerable to thieves and other harmful users. In some cases, an identity thief steals the credentials of a legitimate user (e.g., login and password, credit card number, Medicare number, etc.) and makes purchases or accesses information without the knowledge of and/or authorization of the legitimate user. In some other cases, the owner of the credentials is the one doing the stealing. For example, an employee may be stealing intellectual property or trade secrets. Techniques which detect these unauthorized accesses would be desirable. Furthermore, it would be desirable if these techniques are able to sort through and process massive amounts of data (e.g., “big data”).